Polyamide particles has been used in a wide variety of applications including cosmetics, additives to, for example, paints and waxes, lubricants, adhesives and antiadhesive agents. As examples of a manufacturing process therefor, there are known a process comprising blending Nylon 12 (polyamide 12) and dipropyleneglycol, heating the mixture for dissolution to give a homogeneous solution, and then cooling the solution to precipitate spherical particles of Nylon 12 (Patent Document No. 1); a process for manufacturing a porous polyamide particles comprising blending a solution of polyamide in phenol with methanol and water which are non-solvents to the polyamide (Patent Document No. 2); and a process comprising dissolving a polyamide in ethylene glycol by heating and cooling the solution to produce a spherical polyamide particles powder (Patent Document Nos. 3 and 4).
Among these documents, Patent Document No. 2 has described that porous particles were obtained as described above, and Patent Document No. 4 has described that “particles having porous surface” were obtained (paragraph 0048 and the like). However, in these documents, pores have a particular shape and form, depending on its manufacturing process, and therefore, may not be suitable for a variety of applications. For example, although polyamide particles obtained in Patent Document No. 4 is fine particles with a size of about 12 to 15 μm, it exhibits oil absorption ability of 140 mL/g or less, indicating insufficient porosity.
Furthermore, in a conventional manufacturing process, it is difficult to dry polyamide particles obtained by the manufacturing process by removing a solvent from them without causing the aggregation of particles, and a washing step requires a good deal of washing liquid. A conventional process is, therefore, not preferable in terms of a manufacturing cost and furthermore environmental impact.
Furthermore, there are no known processes for manufacturing polyamide particles using a cyclic amide as a solvent.